The present invention is directed to integrated circuits. More particularly, the invention provides systems and methods for providing power to high-intensity-discharge lamps. Merely by way of example, the invention has been applied for igniting and driving high-intensity-discharge lamps. But it would be recognized that the invention has a much broader range of applicability.
High-Intensity-Discharge (HID) lamps often have high brightness, and provide excellent color rendering. In addition, HID lamps usually enhance visual comfort, and reduce eye fatigue. Because HID lamps do not use incandescent filaments, HID lamps often have a longer lifetime than incandescent lamps.
FIG. 1 is a simplified diagram showing a conventional system 100 for driving an HID lamp 102. The system 100 includes a boost power-factor-corrected (PFC) stage 104, a Buck stage 106, and a full-bridge stage 108. The boost PFC stage 104 includes an inductor 110, a transistor 112, a diode 114, and a capacitor 116. The Buck stage 106 includes a switch 118, a diode 120, an inductor 122, and a resistor 124. The full-bridge stage 108 includes four transistors 126, 128, 130 and 132, a capacitor 134 and two inductors 136 and 138. For example, a chip ground voltage 154 is different from an external ground voltage 158, and a voltage drop 156 on the resistor 124 represents the difference between the chip ground voltage 154 and the external ground voltage 158.
The boost PFC stage 104 outputs a signal 150 to the Buck stage 106. The full-bridge stage 108 receives a signal 152 from the Buck stage 106 for driving the HID lamp 102. The system 100 often has many disadvantages, such as complex circuits, high cost, large short-circuit power consumption, and inadequate protection.
Hence, it is highly desirable to improve techniques for driving (e.g., igniting and/or regulating) an HID lamp.